An objective lens unit for an optical pickup device which is composed of a first optical element including a first element body positioned on an optical information recording medium side and a first annular portion formed on the outer periphery of the first element body, and further composed of a second optical element including a second element body and a second annular light source side of the first element body and a second annular portion formed on the outer periphery of the second element body and coupled to the first annular portion, and at least one of the first and second annular portion has a portion in which the size of outer shape is smaller than the vicinity on at least a part of the light source side.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An objective lens unit for an optical pickup device comprising: a first optical element including: a first element body positioned on an optical information recording medium side; and a first annular portion formed on an outer periphery of the first element body; the objective lens unit further comprising a second optical element including: a second element body positioned on a light source side of the first element body; and a second annular portion formed on an outer periphery of the second element body and coupled to the first annular portion, wherein the first annular portion has a portion in which concave portions extending in an axis direction are formed at a plurality of portions on an outer periphery surface of the first annular portion.
2. An objective lens unit for an optical pickup device comprising: a first optical element including: a first element body positioned on an optical information recording medium side; and a first annular portion formed on an outer periphery of the first element body; the objective lens unit further comprising a second optical element including: a second element body positioned on a light source side of the first element body; and a second annular portion formed on an outer periphery of the second element body and coupled to the first annular portion, wherein second annular portion has a portion in which a size of an outer shape of at least a part of an outer periphery of the second annular portion is smaller on a light source side than on an optical information recording medium side.
3. The objective lens unit of claim 1 , wherein the concave portions are portions in which a radius is reduced on a substantially cylindrical outer periphery surface of the first annular portion.
4. The objective lens unit of claim 1 , wherein the concave portions are portions in which a thickness of the first annular portion is thin.
5. The objective lens unit of claim 1 , wherein radii of bottoms of the concave portions on an outer periphery surface of the first annular portion are smaller than a radius of a portion on a substantially cylindrical outer periphery surface of the second annular portion corresponding to the concave portions by a predetermined amount.
6. The objective lens unit of claim 1 , wherein the concave portions are formed to be equally spaced on an outer periphery of the first annular portion.
7. The objective lens unit of claim 2 , wherein the first annular portion is a cylinder having a first projection protruding toward a light source side from an outer periphery of the first element body and the second annular portion is a cylinder having a second projection protruding toward an optical information recording medium side from an outer periphery of the second element body.
8. The objective lens unit of claim 2 , wherein an outer diameter of a light source side of the second annular portion is smaller than an outer diameter of an optical information recording medium side of the second annular portion.
9. The objective lens unit of claim 2 , wherein the second annular portion has a step having a step surface facing toward a light source side on an outer periphery.
10. The objective lens unit of claim 7 , wherein an outer diameter of an optical information recording medium side end of the second projection is larger than an outer diameter of a light source side end of the first projection.
11. The objective lens unit of claim 7 , wherein an inner diameter of an optical information recording medium side end of the second projection is larger than an inner diameter of a base which is a light source side end of the second projection.
12. The objective lens unit of claim 7 , wherein the second projection has an end surface supporting an end surface of a light source side of the first projection, on an optical information recording medium side.
13. The objective lens unit of claim 2 , wherein the second annular portion has notches on at least a plurality of portions of an outer periphery of a light source side.
14. The objective lens unit of claim 2 , wherein the first optical element and the second optical element are respectively formed integrally as a single unit using a transparent resin to correspond to an objective wavelength.
15. An optical pickup device comprising: an objective lens unit of claim 2 for forming a spot on a recording surface of an optical information recording medium; a holder having a cylindrical shape and a fixing portion for fixing the objective lens unit on an end of the holder by inserting the objective lens unit from a second optical element side, wherein the optical pickup device read information of an optical information medium and write information on an optical information medium.
16. The optical pickup device of claim 15 , wherein a drive actuator portion can be mounted on an outer periphery of the cylindrical holder, and wherein the second annular portion of the second optical element has a fitting portion for fitting the second optical element into an inner surface on an end of the holder and a large diameter portion larger than an inner diameter of the holder and smaller than an outer diameter of the holder.
17. The optical pickup device of claim 15 , wherein a drive actuator portion can be mounted on an outer periphery of the cylindrical holder, and wherein the second optical element has an engaging portion having a step contacting an end of the holder, on an outer periphery of the second annular portion.
18. The objective lens unit of claim 1 , wherein the first annular portion is a cylinder having a first projection protruding toward a light source side from an outer periphery of the first element body and the second annular portion is a cylinder having a second projection protruding toward an optical information recording medium side from an outer periphery of the second element body.
19. The objective lens unit of claim 18 , wherein an inner diameter of a light source side end of the first projection is larger than an inner diameter of a base which is an optical information recording medium side end of the first projection, and wherein an inner diameter of an optical information recording medium side end of the second projection is larger than an inner diameter of a base which is a light source side end of the second projection.
20. An optical pickup device comprising: an objective lens unit of claim 1 for forming a spot on a recording surface of an optical information recording medium; a holder having a cylindrical shape and a fixing portion for fixing the objective lens unit on an end of the holder by inserting the objective lens unit from a second optical element side wherein the optical pickup device is configured to read information from an optical information medium and writes information to an optical information medium.
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February 15, 2006
February 2, 2010
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